End mill chucking structure

Abstract

An end mill chucking structure for chucking an end mill having a relatively small diameter and used, for example, for deep milling of a die. The end mill chucking structure includes an end mill holder and an end mill. A holder body has a taper hole formed therein. The end mill includes an end mill body and a cutting tip provided at an end portion of the end mill body. A portion of the end mill body located opposite the cutting tip serves as a tapered shank portion. The shank portion and the rest of the end mill body are bounded by a shoulder extending outward from the surface of the shank portion. The shank portion is press-fitted or shrink-fitted into the taper hole such that the end face of the holder body abuts the shoulder of the end mill body, through application to the holder body of heat at a temperature lower than a conventional shrink-fitting temperature.

What is claimed is:  
     
       1. An end mill chucking structure comprising: 
       an end mill holder comprising a holder body having a taper hole formed in a front portion thereof, the taper hole tapering down rearward and extending rearward from a front end of the holder body; and  
       an end mill comprising an end mill body and cutting means provided at a front end of the end mill body, a rear portion of the end mill body tapering down rearward and serving as a shank portion, a rear end face of a front portion of the end mill body extending radially outward from an outer circumferential surface of the shank portion,  
       wherein the shank portion of the end mill body is press-fitted or shrink-fitted into the taper hole formed in the holder body through application of heat at a temperature lower than an ordinary shrink-fitting temperature such that the rear end face of the front portion of the end mill body abuts a front end face of the holder body, to thereby fixedly attach the end mill body to the holder body.  
     
     
       2. An end mill chucking structure according to  claim 1 , wherein the rear end face of the front portion of the end mill body extends perpendicularly from the outer circumferential surface of the shank portion. 
     
     
       3. An end mill chucking structure according to  claim 1 , wherein the front portion of the end mill body is formed into a relatively long taper portion which tapers down frontward; a rear end of the taper portion has a diameter smaller than that of the front end face of the holder body; and cutting means is removably attached to the front end portion of the end mill body. 
     
     
       4. An end mill chucking structure according to  claim 1 , wherein the rear end face of the front portion of the end mill body is caused to abut the front end face of the holder body by means of a draw bolt accommodated within the front portion of the holder body, to thereby fixedly attach the end mill body to the holder body. 
     
     
       5. An end mill chucking structure according to  claim 1 , wherein female threads are formed on a wall surface of the taper hole formed in the holder body to thereby form a female-threaded portion; male threads are formed on an outer circumferential surface of a rear portion of the shank portion of the end mill body to thereby form a male-threaded portion; and the male-threaded portion is screwed into the female-threaded portion to thereby fixedly attach the end mill body to the holder body. 
     
     
       6. An end mill chucking structure according to  claim 1 , wherein a groove is formed on a wall surface of the taper hole formed in the holder body so as to discharge fluid therethrough and frontward from the holder body. 
     
     
       7. An end mill chucking structure according to  claim 1 , wherein a small hole is formed in the holder body so as to discharge fluid therethrough and frontward from the holder body. 
     
     
       8. An end mill chucking structure according to  claim 7 , wherein a discharge angle modification member for directing fluid to be discharged from the holder body is disposed at a front end portion of the small hole. 
     
     
       9. The end mill chucking structure according to  claim 1 , wherein the end mill is restrained by the end mill holder on both the rear end face of the front portion and the outer circumferential surface of the shank portion, thereby improving the rigidity of the end mill, preventing vibration of the end mill, and yielding good cutting performance. 
     
     
       10. An end mill chucking structure comprising: 
       a tool holder;  
       an adapter having a shank portion and an arbor portion, the shank portion being fixedly attached to said tool holder and having a predetermined length, the arbor portion having a predetermined length extending coaxially from a front end of the shank portion and tapering down frontward, a taper hole having a predetermined depth being formed coaxially in the arbor portion and extending from a front end of the arbor portion toward the shank portion; and  
       an end mill having a mill body portion and a taper shank portion, the mill body portion having a cutting edge at a front end portion thereof, the taper shank portion extending do axially from a rear end of the mill body portion and being removably fitted into the taper hole formed in the arbor portion of said adapter, a rear end face of the mill body portion projecting outward from the taper shank portion in a flange-like manner so as to serve as a contact face and abutting a front end face of the arbor portion of said adapter upon fitting of the taper shank portion into the taper hole.  
     
     
       11. An end mill chucking structure according to  claim 10 , wherein the contact face is perpendicular to the outer circumferential surface of the taper shank portion. 
     
     
       12. An end mill chucking structure according to  claim 10 , wherein the shank portion of said adapter is straight or tapered. 
     
     
       13. An end mill chucking structure according to  claim 10 , wherein a front end portion of the; arbor portion of said adapter including at least the taper hole is made of steel having a coefficient of thermal expansion greater than that of cemented carbide, and a remaining portion of said adapter including the shank portion is made of cemented carbide. 
     
     
       14. An end mill chucking structure according to  claim 13 , wherein the front end portion of the arbor portion of said adapter is connected to the remaining portion of said adapter by use of connection means. 
     
     
       15. An end mill chucking structure according to claim  13 , wherein a passage is formed in said adapter and end mill so as to supply fluid therethrough to a cutting point. 
     
     
       16. An end mill chucking structure according to  claim 10 , wherein a locking mechanism for preventing rotation of said end mill is provided at a portion at which the end mill is coaxially attached to the front end portion of the arbor portion. 
     
     
       17. An end mill chucking structure according to  claim 16 , wherein the locking mechanism comprises a locking screw screwed removably into a female-threaded hole formed perpendicular to an axis of said adapter in the front end portion of the arbor portion of said adapter and extending from an outer surface of the arbor portion to the taper hole formed in the arbor portion, and a flat portion formed axially at an end portion of the taper shank portion of said end mill, and wherein the locking screw and the flat portion engage with each other to thereby prevent rotation of said end mill press-fitted or shrink-fitted Into the arbor portion of said adapter. 
     
     
       18. An end mill chucking structure according to  claim 16 , wherein the locking mechanism comprises a locking pin inserted removably into a through-hole formed perpendicular to an axis of said adapter in the front end portion of the arbor portion of said adapter, and a groove formed on a rear end face of the taper shank portion of said end mill, and wherein the locking pin and the groove engage with each other to thereby prevent rotation of said end mill press-fitted or shrink-fitted into the arbor portion of said adapter.